Not applicable
Not Applicable
This invention relates to gravity-powered toy vehicles, such as a model roller coaster, operating on an inclined plane. It also relates to the use of an energy-storing flywheel, and permanent magnets for improved traction.
Model roller coaster toys have been built for many years by both hobbyists and toy manufacturers, but have not caught on with the general public in the same manner as model trains, cars or airplanes. This lack of interest is in spite of the current great popularity of amusement parks and the ever increasing number of roller coasters as park centerpieces. Most existing model roller coasters operate in the same manner as full-size roller coasters. They are powered only by the force of gravity over a series of hillsxe2x80x94following the physical laws of motion for free-fall of an essentially frictionless body on an inclined plane track. The problem with these models is that although they may be physically realistic the dynamic motion of the vehicle is quite unrealistic because the apparent speed is far too fast.
To be realistic the velocity of a model should be reduced in proportion to the scale of the model. However, because existing models and full-size roller coasters both follow the same physical laws of free-fall motion the velocity of existing models at any given distance down the track is the same as for a full-size roller coaster. This means, for example, that the time for a real roller coaster to roll just four feet down a 200 foot high track is about the same as a model roller coaster takes to reach the bottom of a four foot high model trackxe2x80x94quite unrealistic. It can be shown that the apparent velocity of a model, allowed to roll in unrestrained free-fall, is multiplied by the square root of the model""s dimensional scale factor. For example, a model scaled to {fraction (1/50)} size, will reach a maximum apparent velocity on the first hill of 495 miles per hour rather than the 70 miles per hour maximum velocity typically reached by real roller coasters. This effect is independent of model configuration, and due only to the physical laws of free-fall motion.
Another problem with existing model roller coasters is that because they run so fast they tend to fly off the track (as could be expected of a real roller coaster running at speeds of up to 495 miles per hour).
The present invention uses the energy-storing property of a flywheel to eliminate this problem by reducing the velocity of the toy vehicle. It also uses the attraction force of permanent magnets to extend the practical implementation of the invention to operate on steep slopes in a low energy loss environment whereby the stored flywheel energy is released to propel the vehicle back up ascending track slopes just as with real roller coasters.
The use of flywheels in toy vehicles is not new. There are a number of examples in the prior art. However, the use of a flywheel to convert a portion of the potential energy of a gravity-powered toy vehicle into rotational kinetic energy rather than translational kinetic energy is unique. Likewise, the use of magnetic attraction in toy vehicles is not new, but it is the combination of this feature with the flywheel feature and the feature of low frictional energy loss that provides the unique and unexpected results provided by the subject invention. The flywheel feature alone combined with low frictional energy loss provides the unexpected result of the subject invention on relatively low inclined plane slopes. However, combining the flywheel feature with the magnetic attraction feature provides the unexpected results with the aggressive steep slopes characteristic of real roller coasters. The magnetic attraction feature provides the necessary traction with minimum loss of energy to achieve the results of the subject invention. Without combining these features the vehicle would be a much less realistic and exciting toy.
U.S. Pat. No. 5,118,320 describes a model roller coaster that is characteristic of existing gravity-powered toy vehicles operating in free-fall motion on a track of complex configuration. Because the model motion is unrestrained the velocity of the vehicle, unlike with the subject invention, is quite unrealistic for the model""s scale.
U.S. Pat. No. 4,443,967 describes a flywheel driven toy car. The flywheel is powered by manually pushing on the car before releasing it. It is not designed to be used as a gravity-powered vehicle, such as a model roller coaster, both because it has high frictional energy loss, and because it would tend to slide rather than roll down relatively mild track slopes.
U.S. Pat. No. 4,031,661 describes the use of permanent magnets in a motor-powered toy racing car to improve traction for acceleration and to prevent skidding on curves. U.S. Pat. No. 3,810,515 describes use of magnetic wheels on a wall climbing device to cause it to adhere to vertical walls of ferrous material. However, neither invention can be used to perform the function of the subject invention, because neither uses a true flywheel, and because both operate with high frictional energy loss which would preclude operation on an ascending track using energy stored within the vehicle.
The subject invention provides a practical solution to the problem of dynamic motion realism in a gravity-powered toy vehicle operating on descending and ascending track slopes. Without this solution gravity-powered toy vehicles, no matter how realistic in physical appearance, lack the essential element of motion realism. The unobviousness of the subject invention is apparent from the fact that the problem has existed for decades without solution in the crowded field of miniature toy vehicles.
The preferred embodiment of the present invention uses an energy-storing flywheel, coupled to the wheels of a gravity-powered toy vehicle, such as a roller coaster, to reduce its velocity so it approaches that which is proportionately realistic for the model scale. The term gravity-powered means the toy vehicle is powered substantially by the force of gravity alone with no other source of power either internal or external to the toy vehicle after it is first raised to a point of elevation The initial potential energy of the vehicle is mostly conserved over the course of the track comprised of both descending and ascending track slopes just as with a real roller coaster. At all points on the track the velocity of the model vehicle is reduced by a constant factor compared to an unrestrained free-fail model vehicle. Thus the dynamic velocity profile of the toy vehicle is the same as for an unrestrained gravity-powered vehicle throughout its descending and ascending journey, but at a proportionately reduced velocity.
In one embodiment of the present invention the flywheel is mounted on the same axle as the vehicle wheels. In that configuration the flywheel diameter must be larger than the wheel diameter in order to achieve sufficient rotational kinetic energy, and must therefore extend below the plane of the vehicle wheels. This requires a track support mechanism that provides clearance for the flywheel.
With real roller coasters and previous embodiments of roller coaster models there is minimal need for traction between the vehicle wheels and track since the vehicle is in a normal free-fall condition. However, with the preferred embodiments of the present invention, traction between the vehicle wheel and the track is needed to supply the force needed to turn the flywheel without the wheel slipping. These embodiments provide for the use of magnetic attraction between the vehicle and track using permanent magnets in either the wheel or vehicle chassis, and a ferromagnetic material in the track. The force of attraction increases the instantaneous static friction between the rolling wheel and track at their point of contact in order to provide increased traction, but since there is no sliding friction there is minimal energy loss.